Detailed structural investigations are being carried out on several glycoproteins with the aim of characterizing the nature of the carbohydrate units and of the glycopeptide bonds present in these molecules. Both soluble and insoluble carbohydrate-containing proteins are under study. These include fetuin, thyroglobulin, glomerular basement membrane, lens capsule, annelid cuticles, plasma membranes and collagens from various sources.